/*
 *    Copyright (C) 2012 Hai Bison
 *
 *    See the file LICENSE at the root directory of this project for copying
 *    permission.
 */

package group.pals.desktop.app.apksigner.utils.ui;

import java.awt.Color;
import java.awt.Component;
import java.awt.Container;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.dnd.DnDConstants;
import java.awt.dnd.DropTarget;
import java.awt.dnd.DropTargetDragEvent;
import java.awt.dnd.DropTargetDropEvent;
import java.awt.dnd.DropTargetEvent;
import java.awt.dnd.DropTargetListener;
import java.awt.event.HierarchyEvent;
import java.awt.event.HierarchyListener;
import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.PrintStream;
import java.io.Reader;
import java.net.URI;
import java.util.ArrayList;
import java.util.EventObject;
import java.util.List;
import java.util.TooManyListenersException;

import javax.swing.BorderFactory;
import javax.swing.JComponent;
import javax.swing.border.Border;

/**
 * This class makes it easy to drag and drop files from the operating system to
 * a Java program. Any <tt>Component</tt> can be dropped onto, but only
 * <tt>JComponent</tt>s will indicate the drop event with a changed border.
 * <p/>
 * To use this class, construct a new <tt>FileDrop</tt> by passing it the target
 * component and a <tt>Listener</tt> to receive notification when file(s) have
 * been dropped. Here is an example:
 * <p/>
 * <code><pre>
 *      JPanel myPanel = new JPanel();
 *      new FileDrop( myPanel, new FileDrop.Listener()
 *      {   public void filesDropped( File[] files )
 *          {   
 *              // handle file drop
 *              ...
 *          }   // end filesDropped
 *      }); // end FileDrop.Listener
 * </pre></code>
 * <p/>
 * You can specify the border that will appear when files are being dragged by
 * calling the constructor with a <tt>Border</tt>. Only <tt>JComponent</tt>s
 * will show any indication with a border.
 * <p/>
 * You can turn on some debugging features by passing a <tt>PrintStream</tt>
 * object (such as <tt>System.out</tt>) into the full constructor. A
 * <tt>null</tt> value will result in no extra debugging information being
 * output.
 * <p/>
 * 
 * <p>
 * I'm releasing this code into the Public Domain. Enjoy.
 * </p>
 * <p>
 * <em>Original author: Robert Harder, rharder@usa.net</em>
 * </p>
 * <p>
 * 2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support added.
 * </p>
 * 
 * @author Robert Harder
 * @author rharder@users.sf.net
 * @version 1.0.1
 */
public class FileDrop {

    private transient Border normalBorder;
    private transient DropTargetListener dropListener;
    private final PrintStream mPrintStream;

    /** Discover if the running JVM is modern enough to have drag and drop. */
    private static Boolean supportsDnD;

    // Default border color
    private static Color defaultBorderColor = new Color(0f, 0f, 1f, 0.25f);

    /**
     * Constructs a {@link FileDrop} with a default light-blue border and, if
     * <var>c</var> is a {@link Container}, recursively sets all elements
     * contained within as drop targets, though only the top level container
     * will change borders.
     * 
     * @param c
     *            Component on which files will be dropped.
     * @param listener
     *            Listens for <tt>filesDropped</tt>.
     * @since 1.0
     */
    public FileDrop(final Component c, final Listener listener) {
        this(
                null, // Logging stream
                c, // Drop target
                BorderFactory.createMatteBorder(2, 2, 2, 2, defaultBorderColor), // Drag
                                                                                 // border
                true, // Recursive
                listener);
    } // end constructor

    /**
     * Constructor with a default border and the option to recursively set drop
     * targets. If your component is a <tt>Container</tt>, then each of its
     * children components will also listen for drops, though only the parent
     * will change borders.
     * 
     * @param c
     *            Component on which files will be dropped.
     * @param recursive
     *            Recursively set children as drop targets.
     * @param listener
     *            Listens for <tt>filesDropped</tt>.
     * @since 1.0
     */
    public FileDrop(final Component c, final boolean recursive,
            final Listener listener) {
        this(
                null, // Logging stream
                c, // Drop target
                BorderFactory.createMatteBorder(2, 2, 2, 2, defaultBorderColor), // Drag
                                                                                 // border
                recursive, // Recursive
                listener);
    } // end constructor

    /**
     * Constructor with a default border and debugging optionally turned on.
     * With Debugging turned on, more status messages will be displayed to
     * <tt>out</tt>. A common way to use this constructor is with
     * <tt>System.out</tt> or <tt>System.err</tt>. A <tt>null</tt> value for the
     * parameter <tt>out</tt> will result in no debugging output.
     * 
     * @param out
     *            PrintStream to record debugging info or null for no debugging.
     * @param out
     * @param c
     *            Component on which files will be dropped.
     * @param listener
     *            Listens for <tt>filesDropped</tt>.
     * @since 1.0
     */
    public FileDrop(final PrintStream out, final Component c,
            final Listener listener) {
        this(
                out, // Logging stream
                c, // Drop target
                BorderFactory.createMatteBorder(2, 2, 2, 2, defaultBorderColor),
                false, // Recursive
                listener);
    } // end constructor

    /**
     * Constructor with a default border, debugging optionally turned on and the
     * option to recursively set drop targets. If your component is a
     * <tt>Container</tt>, then each of its children components will also listen
     * for drops, though only the parent will change borders. With Debugging
     * turned on, more status messages will be displayed to <tt>out</tt>. A
     * common way to use this constructor is with <tt>System.out</tt> or
     * <tt>System.err</tt>. A <tt>null</tt> value for the parameter <tt>out</tt>
     * will result in no debugging output.
     * 
     * @param out
     *            PrintStream to record debugging info or null for no debugging.
     * @param out
     * @param c
     *            Component on which files will be dropped.
     * @param recursive
     *            Recursively set children as drop targets.
     * @param listener
     *            Listens for <tt>filesDropped</tt>.
     * @since 1.0
     */
    public FileDrop(final PrintStream out, final Component c,
            final boolean recursive, final Listener listener) {
        this(
                out, // Logging stream
                c, // Drop target
                BorderFactory.createMatteBorder(2, 2, 2, 2, defaultBorderColor), // Drag
                                                                                 // border
                recursive, // Recursive
                listener);
    } // end constructor

    /**
     * Constructor with a specified border
     * 
     * @param c
     *            Component on which files will be dropped.
     * @param dragBorder
     *            Border to use on <tt>JComponent</tt> when dragging occurs.
     * @param listener
     *            Listens for <tt>filesDropped</tt>.
     * @since 1.0
     */
    public FileDrop(final Component c, final Border dragBorder,
            final Listener listener) {
        this(null, // Logging stream
                c, // Drop target
                dragBorder, // Drag border
                false, // Recursive
                listener);
    } // end constructor

    /**
     * Constructor with a specified border and the option to recursively set
     * drop targets. If your component is a <tt>Container</tt>, then each of its
     * children components will also listen for drops, though only the parent
     * will change borders.
     * 
     * @param c
     *            Component on which files will be dropped.
     * @param dragBorder
     *            Border to use on <tt>JComponent</tt> when dragging occurs.
     * @param recursive
     *            Recursively set children as drop targets.
     * @param listener
     *            Listens for <tt>filesDropped</tt>.
     * @since 1.0
     */
    public FileDrop(final Component c, final Border dragBorder,
            final boolean recursive, final Listener listener) {
        this(null, c, dragBorder, recursive, listener);
    } // end constructor

    /**
     * Constructor with a specified border and debugging optionally turned on.
     * With Debugging turned on, more status messages will be displayed to
     * <tt>out</tt>. A common way to use this constructor is with
     * <tt>System.out</tt> or <tt>System.err</tt>. A <tt>null</tt> value for the
     * parameter <tt>out</tt> will result in no debugging output.
     * 
     * @param out
     *            PrintStream to record debugging info or null for no debugging.
     * @param c
     *            Component on which files will be dropped.
     * @param dragBorder
     *            Border to use on <tt>JComponent</tt> when dragging occurs.
     * @param listener
     *            Listens for <tt>filesDropped</tt>.
     * @since 1.0
     */
    public FileDrop(final PrintStream out, final Component c,
            final Border dragBorder, final Listener listener) {
        this(out, // Logging stream
                c, // Drop target
                dragBorder, // Drag border
                false, // Recursive
                listener);
    } // end constructor

    /**
     * Full constructor with a specified border and debugging optionally turned
     * on. With Debugging turned on, more status messages will be displayed to
     * <tt>out</tt>. A common way to use this constructor is with
     * <tt>System.out</tt> or <tt>System.err</tt>. A <tt>null</tt> value for the
     * parameter <tt>out</tt> will result in no debugging output.
     * 
     * @param out
     *            PrintStream to record debugging info or null for no debugging.
     * @param comp
     *            Component on which files will be dropped.
     * @param dragBorder
     *            Border to use on <tt>JComponent</tt> when dragging occurs.
     * @param recursive
     *            Recursively set children as drop targets.
     * @param listener
     *            Listens for <tt>filesDropped</tt>.
     * @since 1.0
     */
    public FileDrop(final PrintStream out, final Component comp,
            final Border dragBorder, final boolean recursive,
            final Listener listener) {
        mPrintStream = out;
        if (supportsDnD()) { // Make a drop listener
            dropListener = new DropTargetListener() {

                private boolean mDragging = false;

                @Override
                public void dragEnter(DropTargetDragEvent evt) {
                    log(out, "FileDrop: dragEnter event.");

                    if (mDragging)
                        return;

                    // Is this an acceptable drag event?
                    if (isDragOk(out, evt)) {
                        mDragging = true;
                        // If it's a Swing component, set its border
                        if (comp instanceof JComponent && normalBorder == null) {
                            JComponent jc = (JComponent) comp;
                            normalBorder = jc.getBorder();
                            log(out, String.format(
                                    "FileDrop: normal border saved (%s).",
                                    normalBorder));
                            jc.setBorder(dragBorder);
                            log(out, "FileDrop: drag border set.");
                        } // end if: JComponent

                        // Acknowledge that it's okay to enter
                        // evt.acceptDrag(
                        // DnDConstants.ACTION_COPY_OR_MOVE );
                        evt.acceptDrag(DnDConstants.ACTION_COPY);
                        log(out, "FileDrop: event accepted.");
                    } // end if: drag ok
                    else { // Reject the drag event
                        evt.rejectDrag();
                        log(out, "FileDrop: event rejected.");
                    } // end else: drag not ok
                } // end dragEnter

                @Override
                public void dragOver(DropTargetDragEvent evt) {
                    /*
                     * This is called continually as long as the mouse is over
                     * the drag target.
                     */
                } // end dragOver

                @Override
                public void drop(DropTargetDropEvent evt) {
                    log(out, "FileDrop: drop event.");
                    try { // Get whatever was dropped
                        Transferable tr = evt.getTransferable();

                        // Is it a file list?
                        if (tr.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
                            // Say we'll take it.
                            // evt.acceptDrop (
                            // DnDConstants.ACTION_COPY_OR_MOVE );
                            evt.acceptDrop(DnDConstants.ACTION_COPY);
                            log(out, "FileDrop: file list accepted.");

                            // Get a useful list
                            @SuppressWarnings("unchecked")
                            List<File> files = (List<File>) tr
                                    .getTransferData(DataFlavor.javaFileListFlavor);

                            // Alert listener to drop.
                            if (listener != null)
                                listener.onFilesDropped(files
                                        .toArray(new File[0]));

                            // Mark that drop is completed.
                            evt.getDropTargetContext().dropComplete(true);
                            log(out, "FileDrop: drop complete.");
                        } // end if: file list
                        else // this section will check for a reader flavor.
                        {
                            // Thanks, Nathan!
                            // BEGIN 2007-09-12 Nathan Blomquist -- Linux
                            // (KDE/Gnome) support added.
                            DataFlavor[] flavors = tr.getTransferDataFlavors();
                            boolean handled = false;
                            for (int zz = 0; zz < flavors.length; zz++) {
                                if (flavors[zz].isRepresentationClassReader()) {
                                    // Say we'll take it.
                                    // evt.acceptDrop (
                                    // DnDConstants.ACTION_COPY_OR_MOVE
                                    // );
                                    evt.acceptDrop(DnDConstants.ACTION_COPY);
                                    log(out, "FileDrop: reader accepted.");

                                    Reader reader = flavors[zz]
                                            .getReaderForText(tr);

                                    BufferedReader br = new BufferedReader(
                                            reader);

                                    if (listener != null)
                                        listener.onFilesDropped(createFileArray(
                                                br, out));

                                    // Mark that drop is completed.
                                    evt.getDropTargetContext().dropComplete(
                                            true);
                                    log(out, "FileDrop: drop complete.");
                                    handled = true;
                                    break;
                                }
                            }
                            if (!handled) {
                                log(out,
                                        "FileDrop: not a file list or reader - abort.");
                                evt.rejectDrop();
                            }
                            // END 2007-09-12 Nathan Blomquist -- Linux
                            // (KDE/Gnome) support added.
                        } // end else: not a file list
                    } // end try
                    catch (IOException io) {
                        log(out, "FileDrop: IOException - abort:");
                        io.printStackTrace(out);
                        evt.rejectDrop();
                    } // end catch IOException
                    catch (UnsupportedFlavorException ufe) {
                        log(out,
                                "FileDrop: UnsupportedFlavorException - abort:");
                        ufe.printStackTrace(out);
                        evt.rejectDrop();
                    } // end catch: UnsupportedFlavorException
                    finally {
                        restoreNormalBorder(comp);
                        mDragging = false;
                    } // end finally
                } // end drop

                @Override
                public void dragExit(DropTargetEvent evt) {
                    log(out, "FileDrop: dragExit event.");
                    restoreNormalBorder(comp);
                    mDragging = false;
                } // end dragExit

                @Override
                public void dropActionChanged(DropTargetDragEvent evt) {
                    log(out, "FileDrop: dropActionChanged event.");
                    // Is this an acceptable drag event?
                    if (isDragOk(out, evt)) { // evt.acceptDrag(
                                              // DnDConstants.ACTION_COPY_OR_MOVE
                                              // );
                        evt.acceptDrag(DnDConstants.ACTION_COPY);
                        log(out, "FileDrop: event accepted.");
                    } // end if: drag ok
                    else {
                        evt.rejectDrag();
                        log(out, "FileDrop: event rejected.");
                    } // end else: drag not ok
                } // end dropActionChanged
            }; // end DropTargetListener

            // Make the component (and possibly children) drop targets
            makeDropTarget(out, comp, recursive);
        } // end if: supports dnd
        else {
            log(out, "FileDrop: Drag and drop is not supported with this JVM");
        } // end else: does not support DnD
    } // end constructor

    /**
     * Checks and restores normal border of {@code comp} if it's a
     * {@link JComponent}..
     * 
     * @param comp
     *            a component.
     */
    private void restoreNormalBorder(Component comp) {
        log(mPrintStream, "restoreNormalBorder() >> " + comp);
        if (comp instanceof JComponent)
            ((JComponent) comp).setBorder(normalBorder);
        normalBorder = null;
    }// restoreNormalBorder()

    private static boolean supportsDnD() { // Static Boolean
        if (supportsDnD == null) {
            boolean support = false;
            try {
                Class.forName("java.awt.dnd.DnDConstants");
                support = true;
            } // end try
            catch (Exception e) {
                support = false;
            } // end catch
            supportsDnD = new Boolean(support);
        } // end if: first time through
        return supportsDnD.booleanValue();
    } // end supportsDnD

    // BEGIN 2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support added.
    private static String ZERO_CHAR_STRING = "" + (char) 0;

    private static File[] createFileArray(BufferedReader bReader,
            PrintStream out) {
        try {
            List<File> list = new ArrayList<File>();
            String line = null;
            while ((line = bReader.readLine()) != null) {
                try {
                    // kde seems to append a 0 char to the end of the reader
                    if (ZERO_CHAR_STRING.equals(line))
                        continue;

                    File file = new File(new URI(line));
                    list.add(file);
                } catch (Exception ex) {
                    log(out, "Error with " + line + ": " + ex.getMessage());
                }
            }

            return (File[]) list.toArray(new File[list.size()]);
        } catch (IOException ex) {
            log(out, "FileDrop: IOException");
        }
        return new File[0];
    }

    // END 2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support added.

    private void makeDropTarget(final PrintStream out, final Component c,
            boolean recursive) {
        // Make drop target
        final DropTarget dt = new DropTarget();
        try {
            dt.addDropTargetListener(dropListener);
        } // end try
        catch (TooManyListenersException e) {
            e.printStackTrace();
            log(out,
                    "FileDrop: Drop will not work due to previous error. Do you have another listener attached?");
        } // end catch

        // Listen for hierarchy changes and remove the drop target when the
        // parent gets cleared out.
        c.addHierarchyListener(new HierarchyListener() {

            public void hierarchyChanged(HierarchyEvent evt) {
                log(out, "FileDrop: Hierarchy changed.");
                Component parent = c.getParent();
                if (parent == null) {
                    c.setDropTarget(null);
                    log(out, "FileDrop: Drop target cleared from component.");
                } // end if: null parent
                else {
                    new DropTarget(c, dropListener);
                    log(out, "FileDrop: Drop target added to component.");
                } // end else: parent not null
            } // end hierarchyChanged
        }); // end hierarchy listener
        if (c.getParent() != null)
            new DropTarget(c, dropListener);

        if (recursive && (c instanceof Container)) {
            // Get the container
            Container cont = (Container) c;

            // Get it's components
            Component[] comps = cont.getComponents();

            // Set it's components as listeners also
            for (int i = 0; i < comps.length; i++)
                makeDropTarget(out, comps[i], recursive);
        } // end if: recursively set components as listener
    } // end dropListener

    /** Determine if the dragged data is a file list. */
    private boolean isDragOk(final PrintStream out,
            final DropTargetDragEvent evt) {
        boolean ok = false;

        // Get data flavors being dragged
        DataFlavor[] flavors = evt.getCurrentDataFlavors();

        // See if any of the flavors are a file list
        int i = 0;
        while (!ok && i < flavors.length) {
            // BEGIN 2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support
            // added.
            // Is the flavor a file list?
            final DataFlavor curFlavor = flavors[i];
            if (curFlavor.equals(DataFlavor.javaFileListFlavor)
                    || curFlavor.isRepresentationClassReader()) {
                ok = true;
            }
            // END 2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support
            // added.
            i++;
        } // end while: through flavors

        // If logging is enabled, show data flavors
        if (out != null) {
            if (flavors.length == 0)
                log(out, "FileDrop: no data flavors.");
            for (i = 0; i < flavors.length; i++)
                log(out, flavors[i].toString());
        } // end if: logging enabled

        return ok;
    } // end isDragOk

    /** Outputs <tt>message</tt> to <tt>out</tt> if it's not null. */
    private static void log(PrintStream out, String message) { // Log
                                                               // message
                                                               // if
                                                               // requested
        if (out != null)
            out.println(message);
    } // end log

    /**
     * Removes the drag-and-drop hooks from the component and optionally from
     * the all children. You should call this if you add and remove components
     * after you've set up the drag-and-drop. This will recursively unregister
     * all components contained within <var>c</var> if <var>c</var> is a
     * {@link Container}.
     * 
     * @param c
     *            The component to unregister as a drop target
     * @since 1.0
     */
    public static boolean remove(Component c) {
        return remove(null, c, true);
    } // end remove

    /**
     * Removes the drag-and-drop hooks from the component and optionally from
     * the all children. You should call this if you add and remove components
     * after you've set up the drag-and-drop.
     * 
     * @param out
     *            Optional {@link PrintStream} for logging drag and drop
     *            messages
     * @param c
     *            The component to unregister
     * @param recursive
     *            Recursively unregister components within a container
     * @since 1.0
     */
    public static boolean remove(PrintStream out, Component c, boolean recursive) { // Make
                                                                                    // sure
                                                                                    // we
                                                                                    // support
                                                                                    // dnd.
        if (supportsDnD()) {
            log(out, "FileDrop: Removing drag-and-drop hooks.");
            c.setDropTarget(null);
            if (recursive && (c instanceof Container)) {
                Component[] comps = ((Container) c).getComponents();
                for (int i = 0; i < comps.length; i++)
                    remove(out, comps[i], recursive);
                return true;
            } // end if: recursive
            else
                return false;
        } // end if: supports DnD
        else
            return false;
    } // end remove

    /* ******** I N N E R I N T E R F A C E L I S T E N E R ******** */

    /**
     * Implement this inner interface to listen for when files are dropped. For
     * example your class declaration may begin like this: <code><pre>
     *      public class MyClass implements FileDrop.Listener
     *      ...
     *      public void filesDropped( File[] files )
     *      {
     *          ...
     *      }   // end filesDropped
     *      ...
     * </pre></code>
     * 
     * @since 1.1
     */
    public static interface Listener {

        /**
         * This method is called when files have been successfully dropped.
         * 
         * @param files
         *            An array of <tt>File</tt>s that were dropped.
         * @since 1.0
         */
        void onFilesDropped(File[] files);

    } // end inner-interface Listener

    /* ******** I N N E R C L A S S ******** */

    /**
     * This is the event that is passed to the
     * {@link FileDropListener#filesDropped filesDropped(...)} method in your
     * {@link FileDropListener} when files are dropped onto a registered drop
     * target.
     * 
     * <p>
     * I'm releasing this code into the Public Domain. Enjoy.
     * </p>
     * 
     * @author Robert Harder
     * @author rob@iharder.net
     * @version 1.2
     */
    public static class Event extends EventObject {

        /**
         * Auto-generated by Eclipse.
         */
        private static final long serialVersionUID = -3647711483291501728L;

        private File[] files;

        /**
         * Constructs an {@link Event} with the array of files that were dropped
         * and the {@link FileDrop} that initiated the event.
         * 
         * @param files
         *            The array of files that were dropped
         * @source The event source
         * @since 1.1
         */
        public Event(File[] files, Object source) {
            super(source);
            this.files = files;
        } // end constructor

        /**
         * Returns an array of files that were dropped on a registered drop
         * target.
         * 
         * @return array of files that were dropped
         * @since 1.1
         */
        public File[] getFiles() {
            return files;
        } // end getFiles

    } // end inner class Event

    /* ******** I N N E R C L A S S ******** */

    /**
     * At last an easy way to encapsulate your custom objects for dragging and
     * dropping in your Java programs! When you need to create a
     * {@link Transferable} object, use this class to wrap your object. For
     * example:
     * 
     * <pre>
     * <code>
     *      ...
     *      MyCoolClass myObj = new MyCoolClass();
     *      Transferable xfer = new TransferableObject( myObj );
     *      ...
     * </code>
     * </pre>
     * 
     * Or if you need to know when the data was actually dropped, like when
     * you're moving data out of a list, say, you can use the
     * {@link TransferableObject.Fetcher} inner class to return your object Just
     * in Time. For example:
     * 
     * <pre>
     * <code>
     *      ...
     *      final MyCoolClass myObj = new MyCoolClass();
     * 
     *      TransferableObject.Fetcher fetcher = new TransferableObject.Fetcher()
     *      {   public Object getObject(){ return myObj; }
     *      }; // end fetcher
     * 
     *      Transferable xfer = new TransferableObject( fetcher );
     *      ...
     * </code>
     * </pre>
     * 
     * The {@link DataFlavor} associated with {@link TransferableObject} has the
     * representation class <tt>net.iharder.dnd.TransferableObject.class</tt>
     * and MIME type <tt>application/x-net.iharder.dnd.TransferableObject</tt>.
     * This data flavor is accessible via the static {@link #DATA_FLAVOR}
     * property.
     * 
     * 
     * <p>
     * I'm releasing this code into the Public Domain. Enjoy.
     * </p>
     * 
     * @author Robert Harder
     * @author rob@iharder.net
     * @version 1.2
     */
    public static class TransferableObject implements Transferable {

        /**
         * The MIME type for {@link #DATA_FLAVOR} is
         * <tt>application/x-net.iharder.dnd.TransferableObject</tt>.
         * 
         * @since 1.1
         */
        public final static String MIME_TYPE = "application/x-net.iharder.dnd.TransferableObject";

        /**
         * The default {@link DataFlavor} for {@link TransferableObject} has the
         * representation class
         * <tt>net.iharder.dnd.TransferableObject.class</tt> and the MIME type
         * <tt>application/x-net.iharder.dnd.TransferableObject</tt>.
         * 
         * @since 1.1
         */
        public final static DataFlavor DATA_FLAVOR = new DataFlavor(
                FileDrop.TransferableObject.class, MIME_TYPE);

        private Fetcher fetcher;
        private Object data;

        private DataFlavor customFlavor;

        /**
         * Creates a new {@link TransferableObject} that wraps <var>data</var>.
         * Along with the {@link #DATA_FLAVOR} associated with this class, this
         * creates a custom data flavor with a representation class determined
         * from <code>data.getClass()</code> and the MIME type
         * <tt>application/x-net.iharder.dnd.TransferableObject</tt>.
         * 
         * @param data
         *            The data to transfer
         * @since 1.1
         */
        public TransferableObject(Object data) {
            this.data = data;
            this.customFlavor = new DataFlavor(data.getClass(), MIME_TYPE);
        } // end constructor

        /**
         * Creates a new {@link TransferableObject} that will return the object
         * that is returned by <var>fetcher</var>. No custom data flavor is set
         * other than the default {@link #DATA_FLAVOR}.
         * 
         * @see Fetcher
         * @param fetcher
         *            The {@link Fetcher} that will return the data object
         * @since 1.1
         */
        public TransferableObject(Fetcher fetcher) {
            this.fetcher = fetcher;
        } // end constructor

        /**
         * Creates a new {@link TransferableObject} that will return the object
         * that is returned by <var>fetcher</var>. Along with the
         * {@link #DATA_FLAVOR} associated with this class, this creates a
         * custom data flavor with a representation class <var>dataClass</var>
         * and the MIME type
         * <tt>application/x-net.iharder.dnd.TransferableObject</tt>.
         * 
         * @see Fetcher
         * @param dataClass
         *            The {@link Class} to use in the custom data flavor
         * @param fetcher
         *            The {@link Fetcher} that will return the data object
         * @since 1.1
         */
        public TransferableObject(Class<?> dataClass, Fetcher fetcher) {
            this.fetcher = fetcher;
            this.customFlavor = new DataFlavor(dataClass, MIME_TYPE);
        } // end constructor

        /**
         * Returns the custom {@link DataFlavor} associated with the
         * encapsulated object or <tt>null</tt> if the {@link Fetcher}
         * constructor was used without passing a {@link Class}.
         * 
         * @return The custom data flavor for the encapsulated object
         * @since 1.1
         */
        public DataFlavor getCustomDataFlavor() {
            return customFlavor;
        } // end getCustomDataFlavor

        /* ******** T R A N S F E R A B L E M E T H O D S ******** */

        /**
         * Returns a two- or three-element array containing first the custom
         * data flavor, if one was created in the constructors, second the
         * default {@link #DATA_FLAVOR} associated with
         * {@link TransferableObject}, and third the
         * {@link DataFlavor.stringFlavor}.
         * 
         * @return An array of supported data flavors
         * @since 1.1
         */
        public DataFlavor[] getTransferDataFlavors() {
            if (customFlavor != null)
                return new DataFlavor[] { customFlavor, DATA_FLAVOR,
                        DataFlavor.stringFlavor }; // end
                                                   // flavors
                                                   // array
            else
                return new DataFlavor[] { DATA_FLAVOR, DataFlavor.stringFlavor }; // end
                                                                                  // flavors
                                                                                  // array
        } // end getTransferDataFlavors

        /**
         * Returns the data encapsulated in this {@link TransferableObject}. If
         * the {@link Fetcher} constructor was used, then this is when the
         * {@link Fetcher#getObject getObject()} method will be called. If the
         * requested data flavor is not supported, then the
         * {@link Fetcher#getObject getObject()} method will not be called.
         * 
         * @param flavor
         *            The data flavor for the data to return
         * @return The dropped data
         * @since 1.1
         */
        public Object getTransferData(DataFlavor flavor)
                throws UnsupportedFlavorException, IOException {
            // Native object
            if (flavor.equals(DATA_FLAVOR))
                return fetcher == null ? data : fetcher.getObject();

            // String
            if (flavor.equals(DataFlavor.stringFlavor))
                return fetcher == null ? data.toString() : fetcher.getObject()
                        .toString();

            // We can't do anything else
            throw new UnsupportedFlavorException(flavor);
        } // end getTransferData

        /**
         * Returns <tt>true</tt> if <var>flavor</var> is one of the supported
         * flavors. Flavors are supported using the <code>equals(...)</code>
         * method.
         * 
         * @param flavor
         *            The data flavor to check
         * @return Whether or not the flavor is supported
         * @since 1.1
         */
        public boolean isDataFlavorSupported(DataFlavor flavor) {
            // Native object
            if (flavor.equals(DATA_FLAVOR))
                return true;

            // String
            if (flavor.equals(DataFlavor.stringFlavor))
                return true;

            // We can't do anything else
            return false;
        } // end isDataFlavorSupported

        /* ******** I N N E R I N T E R F A C E F E T C H E R ******** */

        /**
         * Instead of passing your data directly to the
         * {@link TransferableObject} constructor, you may want to know exactly
         * when your data was received in case you need to remove it from its
         * source (or do anyting else to it). When the {@link #getTransferData
         * getTransferData(...)} method is called on the
         * {@link TransferableObject}, the {@link Fetcher}'s {@link #getObject
         * getObject()} method will be called.
         * 
         * @author Robert Harder
         * @copyright 2001
         * @version 1.1
         * @since 1.1
         */
        public static interface Fetcher {

            /**
             * Return the object being encapsulated in the
             * {@link TransferableObject}.
             * 
             * @return The dropped object
             * @since 1.1
             */
            public abstract Object getObject();
        } // end inner interface Fetcher

    } // end class TransferableObject

} // end class FileDrop
